Stefan Suurmeijer wrote:

On Sat, 5 Aug 2000, Franky GOETHALS wrote:

...

Hello all,

Since i while i've remarked the following lines in my firewall-log :

Jul 18 21:40:11 penguin dhcpcd[109]: sending DHCP_REQUEST for 213.224.69.28 to 195.130.132.18 Jul 18 21:40:11 penguin kernel: Packet log: input DENY eth0 PROTO=17 195.130.132.18:67 213.224.69.28:68 L=330 S=0x00 I=60193 F=0x4000 T=252 (#127) Jul 18 21:40:11 penguin dhcpcd[109]: DHCP_ACK received from (195.130.132.18)

Does anyone can help me ? I appears to be in the

Stefan, The value of this variable is allready 'yes'. Any other ideas ? Tnx allready, Franky.

...

'critical' messages for the firewall.

What it's telling you is that host 195.130.132.18 is sending an udp (PROTO=17) package to host 213.224.69.28 with bootp information (port 67 & 68) and that package is being denied. If you use the standard Suse firewall configuration script (/etc/rc.config.d/firewall.rc.config) you should have:

FW_SERVICE_DHCLIENT="no" # if you use dhclient to get an ip address # you have to set this to "yes" !

set to yes, or manually add a rule for accepting bootp packages

...

I would like to allow these requests through my firewall, but i didn't succeed. I'm trying to configure it with YAST & FW_- variables in the configuration-file.

Thanks in advance,

Franky.

good luck

Stefan

========================================== Stefan Suurmeijer Network Specialist University of Groningen tel: (+31) 50 363 3423 fax: (+31) 50 363 7272 E-mail (business): s.m.suurmeijer@let.rug.nl E-mail (private): stefan@symbolica.nl ==========================================

Quis custodiet ipsos custodes? (Who'll watch the watchmen?) - Unknown

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-- =================================== GOETHALS Franky Driegaaienstraat 104 B-9100 SINT-NIKLAAS B E L G I E Systeemingenieur Mainframe Tel./Fax : 32 - (0)3 / 776.10.09 GSM : 32 - (0)478 / 21.40.94 franky.goethals@pandora.be ===================================

Stefan Suurmeijer wrote:

On Sun, 6 Aug 2000, Franky GOETHALS wrote:

...

Stefan Suurmeijer wrote:

...

On Sat, 5 Aug 2000, Franky GOETHALS wrote:

...

Hello all,

Since i while i've remarked the following lines in my firewall-log :

Jul 18 21:40:11 penguin dhcpcd[109]: sending DHCP_REQUEST for 213.224.69.28 to 195.130.132.18 Jul 18 21:40:11 penguin kernel: Packet log: input DENY eth0 PROTO=17 195.130.132.18:67 213.224.69.28:68 L=330 S=0x00 I=60193 F=0x4000 T=252 (#127) Jul 18 21:40:11 penguin dhcpcd[109]: DHCP_ACK received from (195.130.132.18)

Does anyone can help me ? I appears to be in the

Stefan,

The value of this variable is allready 'yes'.

Any other ideas ?

Tnx allready,

Franky.

Well, if that value is set to yes, theoretically all traffic coming from system x port 67 to your port 68 should be allowed (see /sbin/SuSEfirewall). If it isn't, you probably defined another rule somewhere specifically denying these connections from this system. To say anything meaningfull, I'd have to take a look at either your firewall.rc.config or your ipchains -L output. What you could do is take a look at your ipchains -L|grep DENY output and see if there's a rule blocking udp connections from the dhcp server. If you really want control over the rules generated, you should use a custom made script instead of SuSEfirewall, adding only those rules you need.

...

...

...

'critical' messages for the firewall.

What it's telling you is that host 195.130.132.18 is sending an udp (PROTO=17) package to host 213.224.69.28 with bootp information (port 67 & 68) and that package is being denied. If you use the standard Suse firewall configuration script (/etc/rc.config.d/firewall.rc.config) you should have:

FW_SERVICE_DHCLIENT="no" # if you use dhclient to get an ip address # you have to set this to "yes" !

set to yes, or manually add a rule for accepting bootp packages

...

I would like to allow these requests through my firewall, but i didn't succeed. I'm trying to configure it with YAST & FW_- variables in the configuration-file.

Stefan

========================================== Stefan Suurmeijer Network Specialist University of Groningen tel: (+31) 50 363 3423 fax: (+31) 50 363 7272 E-mail (business): s.m.suurmeijer@let.rug.nl E-mail (private): stefan@symbolica.nl ==========================================

Quis custodiet ipsos custodes? (Who'll watch the watchmen?) - Unknown

Stefan, In attach my /etc/rc.config.d/firewall.rc.config, and hereunder some other output : root@penguin:/etc > ifconfig eth0 Link encap:Ethernet HWaddr 00:50:04:40:83:11 inet addr:213.224.20.136 Bcast:213.224.21.255 Mask:255.255.254.0 UP BROADCAST NOTRAILERS RUNNING PROMISC MTU:1500 Metric:1 RX packets:155572 errors:0 dropped:0 overruns:0 frame:0 TX packets:119434 errors:0 dropped:0 overruns:0 carrier:1 collisions:0 txqueuelen:100 Interrupt:9 Base address:0x1400 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:3924 Metric:1 RX packets:403 errors:0 dropped:0 overruns:0 frame:0 TX packets:403 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 vmnet1 Link encap:Ethernet HWaddr 00:50:56:01:00:00 inet addr:192.168.164.1 Bcast:192.168.164.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:41310 errors:0 dropped:0 overruns:0 frame:0 TX packets:53743 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 root@penguin:/etc > ipchains -L|grep DENY Chain input (policy DENY): DENY all ----l- 213.224.20.0/23 anywhere n/a DENY all ----l- 192.168.164.0/24 anywhere n/a DENY all ----l- 192.168.164.0/24 anywhere n/a DENY all ----l- 213.168.164.0/24 anywhere n/a DENY all ----l- 213.224.0.0/24 anywhere n/a DENY all ----l- linux anywhere n/a DENY all ----l- dhcp-213-224-20-136.kabel.pandora.be anywhere n/a DENY all ----l- loopback/8 anywhere n/a DENY all ----l- anywhere loopback/8 n/a DENY all ----l- 192.168.164.0/24 linux n/a DENY all ----l- 192.168.164.0/24 dhcp-213-224-20-136.kabel.pandora.be n/a DENY all ----l- 213.168.164.0/24 linux n/a DENY all ----l- 213.168.164.0/24 dhcp-213-224-20-136.kabel.pandora.be n/a DENY all ----l- 213.224.0.0/24 linux n/a DENY all ----l- 213.224.0.0/24 dhcp-213-224-20-136.kabel.pandora.be n/a DENY all ----l- anywhere 192.168.164.0/24 n/a DENY all ----l- anywhere 192.168.164.0/24 n/a DENY all ----l- anywhere 213.168.164.0/24 n/a DENY all ----l- anywhere 213.224.0.0/24 n/a DENY all ----l- anywhere anywhere n/a Chain forward (policy DENY): DENY all ----l- anywhere anywhere n/a I don't get from where he gets all those denies.... Can you please help ? Tnx, Franky. -- =================================== GOETHALS Franky Driegaaienstraat 104 B-9100 SINT-NIKLAAS B E L G I E Systeemingenieur Mainframe Tel./Fax : 32 - (0)3 / 776.10.09 GSM : 32 - (0)478 / 21.40.94 franky.goethals@pandora.be =================================== # Copyright (c) 1999,2000 SuSE GmbH Nuernberg, Germany. All rights reserved. # # Author: Marc Heuse , 1999,2000 # Please contact me directly if you find bugs. # # If you have problems getting this tool configures, please read this file # carefuly and take also a look into /usr/doc/packages/firewals/EXAMPLES ! # # /etc/rc.config.d/firewall.rc.config # # for use with /sbin/SuSEfirewall version 2.1 # # ------------------------------------------------------------------------ # # PLEASE NOTE THE FOLLOWING: # # Just by configuring these settings and using the SuSEfirewall you are # not secure per se! There is *not* such a thing you install and hence you # are safed from all (security) hazards. # # To ensure your security, you must also: # # * Secure all services you are offering to untrusted networks (internet) # You can do this by using software which has been designed with # security in mind (like postfix, apop3d, ssh), setting these up without # misconfiguration and praying, that they have got really no holes. # SuSEcompartment can help in most circumstances to reduce the risk. # * Do not run untrusted software. (philosophical question, can you trust # SuSE or any other software distributor?) # * Harden your server(s) with the harden_suse package/script # * Recompile your kernel with the openwall-linux kernel patch # (former secure-linux patch, from Solar Designer) www.openwall.com # * Check the security of your server(s) regulary # * If you are using this server as a firewall/bastion host to the internet # for an internal network, try to run proxy services for everything and # disable routing on this machine. # * If you run DNS on the firewall: disable untrusted zone transfers and # either don't allow access to it from the internet or run it split-brained. # # Good luck! # # Yours, # SuSE Security Team # # ------------------------------------------------------------------------ # # Configuration HELP: # # If you have got any problems configuring this file, take a look at # /usr/doc/packages/firewals/EXAMPLES for an example. # # # All types have to set option 1): set START_FW in /etc/rc.config to "yes" ;-) # # If you are a end-user who is NOT connected to two networks you just have to # reconfigure (all other settings are OK): 2), and maybe 9), 11), and 17). # # If this server is a firewall, which should act like a proxy (no direct # routing between both networks), or you are end end-user connected to the # internet and to a internal network, you have to setup your proxys and # reconfigure (all other settings are OK): 2), 3), 9) and maybe 7), 10), 11) # 12), 14) and 17). # # If this server is a firewall, and should do routing/masquerading between # the untrusted and the trusted network, you have to reconfigure (all other # settings are OK): 2), 3), 5), 6), 9), and maybe 7), 10), 11), 12), 14), 17). # # If you want to run a DMZ in either of the above three standard setups, you # just have to config 4), 9), 13) and maybe 18). # # If you know what you are doing, you may also change 8), 15), 16), 18) # and the expert options 19), 20), 21) at the far end, but you should NOT. # # If you use diald or ISDN autodialing, you might want to set 17). # # To get programs like traceroutes to your firewall to work is a bit tricky, # you have to set the following options to "yes" : 11 (UDP only), 18 and 19. # # If you want to load the full firewall rules for an interface even if it's not # available, configure a static IP and netmask (see 2, 3 and 4 for an example). # # Please note that if you use service names, that they exist in /etc/services. # There is no service "dns", it's called "domain", email is called "smtp" etc. # # If you use a modem/ISDN for connections, put "/sbin/SuSEfirewall" in the # 2nd line of "/etc/ppp/ip-up". This is important!! # # *Any* routing between interfaces except masquerading has to set FW_ROUTE to # "yes" and use FW_FORWARD_TCP and/or FW_FORWARD_UDP # # If you just want to do masquerading without filtering, ignore this script # and run this line (exchange "ippp0" with your masquerade/external interface): # ipchains -A forward -j MASQ -i ippp0 # # ------------------------------------------------------------------------ # # 1.) # Should the Firewall be started? # # This setting is done in /etc/rc.config (START_FW="yes") # # 2.) # Which is the interface that points to the internet? # # Enter all the network devices here which are untrusted. # # Choice: any number of devices, seperated by a space # e.g. "eth0", "ippp0 ippp1" # FW_DEV_WORLD="eth0" # # You *may* configure a static IP and netmask to force rule loading even if the # interface is not up and running: set a variable called # FW_DEV_WORLD_[device]="IP_ADDRESS NETMASK" # see below for an example. Otherwise automatic detection is done. # #FW_DEV_WORLD_ippp0="10.0.0.1 255.255.255.0" # e.g. for exernal interface ippp0 # # 3.) # Which is the interface that points to the internal network? # # Enter all the network devices here which are trusted. # If you are not connected to a trusted network (e.g. you have just a # dialup) leave this empty. # # Choice: leave empty or any number of devices, seperated by a space # e.g. "tr0", "eth0 eth1" or "" # FW_DEV_INT="vmnet1" # # You may configure a static IP and netmask to force rule loading even if the # interface is not up and running: set a variable called # FW_DEV_INT_[device]="IP_ADDRESS NETMASK" # see below for an example. Otherwise automatic detection is done. # #FW_DEV_INT_eth0="192.168.1.1 255.255.255.0" # e.g. for internal interface eth0 # # 4.) # Which is the interface that points to the dmz network? # # Enter all the network devices here which point to the dmz. # A "dmz" is a special, seperated network, which is only connected to the # firewall, and should be reachable from the internet to provide services, # e.g. WWW, Mail, etc. and hence are at risk from attacks. # See /usr/doc/packages/firewals/EXAMPLES for an example. # # Special note: You have to configure FW_FORWARD_TCP and FW_FORWARD_UDP to # define the services which should be available to the internet and set # FW_ROUTE to yes. # # Choice: leave empty or any number of devices, seperated by a space # e.g. "tr0", "eth0 eth1" or "" # FW_DEV_DMZ="" # # You may configure a static IP and netmask to force rule loading even if the # interface is not up and running: set a variable called # FW_DEV_INT_[device]="IP_ADDRESS NETMASK" # see below for an example. Otherwise automatic detection is done. # #FW_DEV_DMZ_eth1="192.168.1.1 255.255.255.0" # e.g. for dmz interface eth1 # # 5.) # Should routing between the internet, dmz and internal network be activated? # REQUIRES: FW_DEV_INT or FW_DEV_DMZ # # You need only set this to yes, if you either want to masquerade internal # machines or allow access to the dmz (or internal machines, but this is not # a good idea). This option supersedes IP_FORWARD from /etc/rc.config! # # Setting this option one alone doesn't do anything. Either activate # massquerading with FW_MASQUERADE below if you want to masquerade your # internal network to the internet, or configure FW_FORWARD_TCP and/or # FW_FORWARD_UDP to define what is allowed to be forwarded! # # Choice: "yes" or "no", defaults to "no" # FW_ROUTE="yes" # # 6.) # Do you want to masquerade internal networks to the outside? # REQUIRES: FW_DEV_INT, FW_ROUTE # # "Masquerading" means that all your internal machines which use services on # the internet seem to come from your firewall. # Please note that it is more secure to communicate via proxies to the # internet than masquerading # # Choice: "yes" or "no", defaults to "no" # FW_MASQUERADE="yes" # # Which internal computers/networks are allowed to access the internet # directly (not via proxys on the firewall)? # Only these networks will be allowed access and will be masqueraded! # # Choice: leave empty or any number of computers and/or networks, seperated by # a space. You may NOT set this to "0/0" ! # e.g. "10.0.0.0/8", "10.0.0.1 10.0.0.10 10.10.10.0/24" or "" # FW_MASQ_NETS="192.168.164.0/24 213.168.164.0/24 213.224.0.0/24" # # If you want (and you should) you may also set the FW_MASQ_DEV option, to # specify the outgoing interface to masquerade on. (You would normally use # the external interface(s), the FW_DEV_WORLD device(s), e.g. "ippp0") # FW_MASQ_DEV="$FW_DEV_WORLD" # e.g. "ippp0" or "$FW_DEV_WORLD" # # 7.) # Do you want to protect the firewall from the internal network? # REQUIRES: FW_DEV_INT # # If you set this to "yes", internal machines may only access services on # the machine you explicitly allow. They will be also affected from the # FW_AUTOPROTECT_GLOBAL_SERVICES option. # If you set this to "no", any user can connect (and attack) any service on # the firewall. # # Choice: "yes" or "no", defaults to "yes" # FW_PROTECT_FROM_INTERNAL="no" # # 8.) # Do you want to autoprotect all global running services? # # If set to "yes", all network access to services TCP and UDP on this machine # which are not bound to a special IP address will be prevented (except to # those which you explicitly allow, see below: FW_*_SERVICES_*) # Example: "0.0.0.0:23" would be protected, but "10.0.0.1:53" not. # # Choice: "yes" or "no", defaults to "yes" # FW_AUTOPROTECT_GLOBAL_SERVICES="no" # # 9.) # Which services on the firewall should be accessible from either the internet # (or other untrusted networks), the dmz or internal (trusted networks)? # # Enter all ports or known portnames below, seperated by a space. # TCP services (e.g. SMTP, WWW) must be set in FW_SERVICES_*_TCP, and # UDP services (e.g. syslog) must be set in FW_SERVICES_*_UDP. # e.g. if a webserver on the firewall should be accessible from the internet: # FW_SERVICES_EXTERNAL_TCP="www" # e.g. if the firewall should receive syslog messages from the dmz: # FW_SERVICES_DMZ_UDP="syslog" # # Choice: leave empty or any number of ports, known portnames (from # /etc/services) and port ranges seperated by a space. Port ranges are # written like this, from 1 to 10: "1:10" # e.g. "", "smtp", "123 514", "3200:3299", "ftp 22 telnet 512:514" # FW_SERVICES_EXTERNAL_TCP="www smtp telnet telnet5 ftp-data ipp compressnet" FW_SERVICES_EXTERNAL_UDP="www smtp telnet telnet5 ftp-data ipp compressnet" # FW_SERVICES_DMZ_TCP="" FW_SERVICES_DMZ_UDP="" # FW_SERVICES_INTERNAL_TCP="" FW_SERVICES_INTERNAL_UDP="" # # 10.) # Which services should be accessible from trusted hosts/nets on the internet? # # Define trusted networks on the internet, and the TCP and/or UDP services # they are allowed to use. # # Choice: leave FW_TRUSTED_NETS empty or any number of computers and/or # networks, seperated by a space. e.g. "172.20.1.1", "172.20.0.0/16" # FW_TRUSTED_NETS="213.224.0.0/0 10.95.13.0/0 192.168.164.0/0" # # leave FW_SERVICES_TRUSTED_* empty or any number of ports, known portnames # (from /etc/services) and port ranges seperated by a space. # e.g. "25", "ssh", "1:65535", "1 3:5" # FW_SERVICES_TRUSTED_TCP="1:65535" FW_SERVICES_TRUSTED_UDP="1:65535" # # 11.) # How is access allowed to high (unpriviliged [above 1023]) ports? # # You may either allow everyone from anyport access to your highports ("yes"), # disallow anyone ("no"), anyone who comes from a defined port (portnumber or # known portname) [note that this is easy to circumvent!], or just your # defined nameservers ("dns"). # Note that if you want to use normal (active) ftp, you have to set the TCP # option to ftp-data. If you use passive ftp, you don't need that. # Note that you can't use rpc requests (e.g. rpcinfo, showmount) as root # from a firewall using this script. # # Choice: "yes", "no", "dns", portnumber or known portname, defaults to "no" # FW_ALLOW_INCOMING_HIGHPORTS_TCP="yes" FW_ALLOW_INCOMING_HIGHPORTS_UDP="yes" # # 12.) # Are you running some of the services below? # They need special attention - otherwise they won´t work! # # Set services you are running to "yes", all others to "no", defaults to "no" # FW_SERVICE_DNS="no" # if yes, FW_TCP_SERVICES_* needs to have port 53 # (or "domain") set to allow incoming queries. # also FW_ALLOW_INCOMING_HIGHPORTS_UDP needs to be "yes" FW_SERVICE_DHCLIENT="yes" # if you use dhclient to get an ip address # you have to set this to "yes" ! FW_SERVICE_DHCPD="yes" # # 13.) # Which services accessed from the internet should be allowed to the # dmz or internal network? # REQUIRES: FW_ROUTE # # With this option you may allow access to e.g. your mailserver. The # machines must have valid, non-private, IP addresses which were assigned to # you by your ISP. This opens a direct link to your network, so only use # this option for access to your dmz!!!! # # Choice: leave empty (good choice!) or use the following explained syntax # of forwarding rules, seperated each by a space. # A forwarding rule consists of 1) source IP/net, 2) destination IP (dmz/intern) # and 3) destination port, seperated by a comma (","), e.g. # "4.0.0.0/8,1.1.1.1,22", # "4.4.4.4/12,20.20.20.20,22 12.12.12.12/12,20.20.20.20,22" # FW_FORWARD_TCP="" FW_FORWARD_UDP="" # # 14.) # Which accesses to services should be redirected to a localport on the # firewall machine? # This can be used to force all internal users to surf via your squid proxy, # or transparently redirect incoming webtraffic to a secure webserver. # # Choice: leave empty or use the following explained syntax of redirecting # rules, seperated by a space. # A redirecting rule consists of 1) source IP/net, 2) destination IP/net, # 3) original destination port and 4) local port to redirect the traffic to, # seperated by a colon. e.g. "10.0.0.0/8,0/0,80,3128 0/0,172.20.1.1,80,8080" # FW_REDIRECT_TCP="" FW_REDIRECT_UDP="" # # 15.) # Which logging level should be enforced? # You can define to log packets which were accepted or denied. # You can also the set log level, the critical stuff or everything. # Note that logging *_ALL is only for debugging purpose ... # # Choice: "yes" or "no", FW_LOG_*_CRIT defaults to "yes", # FW_LOG_*_ALL defaults to "no" # FW_LOG_DENY_CRIT="yes" FW_LOG_DENY_ALL="yes" FW_LOG_ACCEPT_CRIT="no" FW_LOG_ACCEPT_ALL="no" # # 16.) # Do you want to enable additional kernel TCP/IP security features? # If set to yes, some obscure kernel options are set. # (icmp_ignore_bogus_error_responses, icmp_echoreply_rate, # icmp_destunreach_rate, icmp_paramprob_rate, icmp_timeexeed_rate, # ip_local_port_range, log_martians, mc_forwarding, mc_forwarding, # rp_filter, routing flush) # Tip: Set this to "no" until you have verified that you have got a # configuration which works for you. Then set this to "yes" and keep it # if everything still works. (It should!) ;-) # # Choice: "yes" or "no", defaults to "yes" # FW_KERNEL_SECURITY="yes" # # 17.) # Keep the routing set on, if the firewall rules are unloaded? # REQUIRES: FW_ROUTE # # If you are using diald, or automatic dialing via ISDN, if packets need # to be sent to the internet, you need to turn this on. The script will then # not turn off routing and masquerading when stopped. # You *might* also need this if you have got a DMZ. # Please note that this is *insecure*! If you unload the rules, but are still # connected, you might your internal network open to attacks! # The better solution is to remove "/sbin/SuSEfirewall stop" or # "/sbin/init.d/firewall stop" from the ip-down script! # # # Choices "yes" or "no", defaults to "no" # FW_STOP_KEEP_ROUTING_STATE="no" # # 18.) # Allow (or don't) ICMP echo pings on either the firewall or the dmz from # the internet? # REQUIRES: FW_ROUTE for FW_ALLOW_PING_DMZ # # Choice: "yes" or "no", defaults to "no" # FW_ALLOW_PING_FW="yes" FW_ALLOW_PING_DMZ="yes" ## # END of rc.firewall ## # # #-------------------------------------------------------------------------# # # # EXPERT OPTIONS - all others please don't change these! # # # #-------------------------------------------------------------------------# # # # # 19.) # Allow (or don't) ICMP time-to-live-exceeded to be send from your firewall. # This is used for traceroutes to your firewall (or traceroute like tools). # # Please note that the unix traceroute only works if you say "yes" to # FW_UDP_ALLOW_INCOMING_HIGHPORTS, and windows traceroutes only if you say # "yes" to FW_ALLOW_PING_FW # # Choice: "yes" or "no", defaults to "no" # FW_ALLOW_FW_TRACEROUTE="yes" # # 20.) # Allow ICMP sourcequench from your ISP? # If set to yes, the firewall will notice when connection is choking, however # this opens yourself to a denial of service attack. Choose your poison. # # Choice: "yes" or "no", defaults to "yes" # FW_ALLOW_FW_SOURCEQUENCH="yes" # # 21.) # Which masquerading modules should be loaded? # REQUIRES: FW_ROUTE, FW_MASQUERADE # # (omit the path or "ip_masq_" prefix as well as the ".o" suffix!) # FW_MASQ_MODULES="autofw cuseeme ftp irc mfw portfw quake raudio user vdolive"